Threading procedure

ABSTRACT

Two contiguous conveyor belts for threading a pulp web tail through a dryer to avoid bunching and consequent tearing or cutting of the web tail by means of a paper tape such as those found on adding machines between the web and one belt. The paper tape allows relative slippage between one belt and the web tail so that the web does not have to try to conform with the local speed differences between the belts as they pass successively through direction reversing rolls.

United States Patent [72] Inventor Harry Knelson Prince Rupert, Canada[21] Appl No. 866,350

[22] Filed [45] Patented [73] Assignee Oct. 14, 1969 Dec. 28, 1971Aktiebolaget Svenska Flaktiabriken Stockholm, Sweden [32] Priority May26, 1969 [33] Canada [54] THREADING PROCEDURE 3 Claims, 4 Drawing Figs.

52 05.01 34/23, 34/158 51 mac! F26b3/00 [50] Field of Search 34/23. 158

[56] References Cited UNITED STATES PATENTS 3,399,465 9/1968 Lanne etal. 34/158 Primary Examiner-Charles Sukalo Attorney-Howson and HowsonABSTRACT: Two contiguous conveyor belts for threading a pulp web tailthrough a dryer to avoid bunching and consequent tearing or cutting ofthe web tail by means of a paper tape such as those found on addingmachines between the web and one belt. The paper tape allows relativeslippage between one belt and the web tail so that the web does not haveto try to conform with the local speed differences between the belts asthey pass successively through direction reversing rolls.

PATENTEUnmzmsn 3,629,949

SHEET 2 BF 3 FULL WIDTH WEB 2 PATENTEI] UEE28 Ian SHEET 3 []F 3THREADING PROCEDURE The invention relates to the problem of threadingthe leading edge of a web material such as cellulose pulp to and frobetween two opposed series of rolls as found in dryers and pulpmachinery of a similar nature.

Such a threading arrangement usually comprises a conveyor mounted at oneside of the path through which the whole web will eventually pass; andthe conveyor itself comprises two similar endless belts which passtogether successively over one end of each roll. The start of the web isusually a long narrow strip at one edge which broadens out gradually tothe full web width; this facilitates threading and is usually called thetail of the web or pulp.

This pulp tail is gripped between the two endless belts at the beginningof the path; these belts thread the tail through the roll path andrelease the tail at the end of the path, so that the tail pulls the fullwidth web through the rolls after it.

Unfortunately, a serious disadvantage is that it is very difficult toget the two belts running at exactly the same speed; for example, as thetwo belts pass over successive rolls the inner slower belt adjacent oneroll becomes the outer faster belt of the next roll displaced from it bythe thickness of the other belt. This means that one belt must slidelocally with respect to the other, and other factors may also contributeto and accentuate the speed difference between the two belts, as is wellknown to those skilled in the art.

The result of this speed difference depends upon the material of thepulp web. Some may disintegrate and in other cases when a pulp tail isgripped between two belts not running at precisely the same speed it cancause the tail to bunch" or fold onto itself so as to foreshorten thetail. When such a bunch passes over a roll the pressure applied on thepulp tail causes the tail to be cut at each fold. The effect isparticularly damaging to hardwood pulp tails as the tensile strength ofhardwood pulp is generally considerably less than that of softwood pulp.

A previous solution to the problem has been disclosed in U.S. Pat. No.3,399,465 issued Sept. 3, 1968 and assigned to the assignee of thepresent application, disclosure of this patent being incorporated hereinby reference. The problem was overcome by providing a single belt (ortwo belts joined at the edge) to obviate slipping; this requiredconveyor modification to fold the belt into two at the beginning so asto grip the tail and to unfold it at the end of the threading so as torelease the pulp tail and to pass the belt back to the beginning.

I have found that the disadvantages of the prior art using two separatebelts may be overcome by facing one belt with a strip of smoothmaterial. In a preferred embodiment I feed a strip of strong smoothmaterial in with the pulp tail. Although I do not wish to be bound bythis explanation, I consider that what happens is that the smoothmaterial allows one belt to slip while the other belt grips the pulptail and threads it through the dryer. However, it may be that thepredominant effect is one of reinforcement. Preferably this material ispaper tape, the type used in adding machinesother suitable materials canbe determined in ordinary trial and error experiment by those skilled inthe art.

The invention may best be understood by reference to the drawings inwhich:

FIG. 1 is a sectional view showing conventional arrange-;

ments;

FIG. 2 is a vertical cross section through the same plant along the lineA-A in FIG. 1, showing the treatment plant in normal operation;

FIG. 3 is the same vertical cross section as in FIG. 2 showing thetreatment plant during the threading of the web material;

FIG. 4 shows an enlarged view of the pulp tail and the tape at initialentry between the two belts as in the preferred embodiment.

In FIG. 1, the treatment plant 2, in this case a dryer, is enclosed inhousing 4, and the full width paper webwhen fully threaded enters thedryer at the left (although not in the plane of the section shown so asto avoid the threading arrangement 6) and passes over rollers 8, l0, 12through 22 successively. It will be understood that the dryer extends atright angles to the plane of the paper and that the section of FIG. I isat one end of the rollers as is the box 6 for the threadingarrangements, although slot 24 extends substantially along the length ofand parallel to the axis of the rollers. The ducts for the drying medium26 may extend as far as the plane of the threading arrangement at theend of the rollers but do not relate to the invention.

In the conventional threading operation the pulp tail 28 is grippedbetween two separate and independent belts 30 and 32 which come togetherafter leaving their independent idler rollers 34, 36. The three layers(of belt 30, belt 32 and pulp tail 28) pass together under idler 38,over idlers 40 and 42 into the roll system (8 through 22) of the dryeras shown. As can be clearly seen afterpassing over roll 22, the beltsseparate to free the pulp tail, each belt being returned independentlyto the beginning. This is accomplished by a series of idlers 44 andtensioning weight 46 for belt 30 and idlers 50 and tensioning weight 48for belt 32.

In FIG. 2 the plant is shown in normal operation. The spaces between thecross-hatched portions represent the ducts 26. In each deck a conveyor58 is located to the side of the material web. This conveyor is notengaged in normal operation.

In FIG. 3 the plant is shown in the threading operation. The leading end28 has been introduced into the conveyor 54 and is threaded by itthrough the rolls.

FIG. 4 illustrates the insertion of the tape in the instant inventionwhich is shown as a spool 52 which is preferably of ordinary, readilyavailable adding machine paper tape. This tape should, of course, bewide enough to substantially prevent any contact of the adjacent beltand the tail and I find that 4-inch wide paper tape is suitable.

The paper tape itself 54 is fed into the conveyor belt with the pulptail and is started as soon as or somewhat ahead of the pulp tail. Thepaper tape feed is continued until the pulp tail leaves the dryer beltsso as to ensure that proper threading has taken place.

The support 56 for the spool of paper tape may be located at anyconvenient place although I have shown it below the pulp tail 28 so thatit can be conveniently mounted on the threading arrangement box 6 or thehousing 4.

Thus, it will be seen that this invention enables a pulp tail to bethreaded through a series of rolls with only a minor modification toprior art threading arrangements.

I claim: I. A method for threading a pulp web through a series of rollscomprising the steps of:

providing one conveyor belt with a normal facing and providing a secondconveyor belt with a smooth facing,

gripping the web on a narrow edge portion between said two conveyorbelts in face to face relationship of the normal and smooth facing,

passing the belts through the series of rolls, and

separating the belts so as to release the pump web narrow edge portionafter passage through the series of rolls.

2. A method for threading a pulp web through a series of rollscomprising the steps of:

facing a first conveyor belt with a tape of strong smooth material,

juxtaposing a second conveyor belt in face to face relationship withsaid first conveyor belt with the tape vtherebetween,

gripping a pulp tail between the face of the second belt and the tape,

passing the two belts through the series of rolls, and

separating the belts so as to release the pulp tail after passagethrough the series of rolls.

3. A method of threading a pulp web through a series of rolls comprisingthe steps of:

facing a conveyor belt with a layer of paper tape,

juxtaposing a second conveyor belt in face to face relationship withsaid first conveyor belt with the paper tape therebetween,

gripping a pulp tail between the face of the second belt and the tape,passing the two belts through the series of rolls, and separating thebelts so as to release the pulp tail after passage through the series ofrolls. 5

i l i

2. A method for threading a pulp web through a series of rollscomprising the steps of: facing a first conveyor belt with a tape ofstrong smooth material, juxtaposing a second conveyor belt in face toface relationship with said first conveyor belt with the tapetherebetween, gripping a pulp tail between the face of the second beltand the tape, passing the two belts through the series of rolls, andseparating the belts so as to release the pulp tail after passagethrough the series of rolls.
 3. A method of threading a pulp web througha series of rolls comprising the steps of: facing a conveyor belt with alayer of paper tape, juxtaposing a second conveyor belt in face to facerelationship with said first conveyor belt with the paper tapetherebetween, gripping a pulp tail between the face of the second beltand the tape, passing the two belts through the series of rolls, andseparating the belts so as to release the pulp tail after passagethrough the series of rolls.